Howard met with Nets owner Mikhail Prokhorov and general manager Billy King in Miami, sources said. Howard was joined by a few business associates.
The meeting violates the NBA's tampering rules because Howard's current team, the Orlando Magic, did not know about the meeting or give the Nets permission to meet with him, according to the sources.
In a telephone conversation Friday afternoon, Howard denied meeting with the Nets Thursday night, saying "there was no meeting."
Howard continued, "Right now, my plan is to show up to training camp for the Orlando Magic."
King added in a statement: "Contrary to published reports, the New Jersey Nets did not meet with Dwight Howard."
Nonetheless, several sources insist the meeting took place.
Nets star Deron Williams said he didn't know anything about the meeting.
"I don't even pay attention to that stuff. ... That's rumors and sources," he said. "We can't be worried about that. All we can do is concentrate on what's going on here out on the court."
NBA.com reported that the Magic are considering filing tampering charges against two teams, one being the Nets. SI.com reported that the other team is the Houston Rockets.
Magic CEO Alex Martins denied the tampering charges.
"There aren't any tampering charges. Dwight is under contract with us and our rules in the league are very explicit about when a player is under contract with a team other teams aren't allowed to contact that player or a representative about them,'' said Martins, according to NBA.com. "If that's been voided in any way we'll deal with it to the fullest extent that the NBA's Constitution allows. But at this stage there aren't any tampering charges.''
The meeting was the first between Howard and the Nets, but the second between Howard's representatives and the Nets.
At the meeting, the group discussed a deal in which Howard would be traded to New Jersey. The plan was for Howard to ask Orlando to trade him Friday morning.
Sources said the Magic had been discussing a possible trade with New Jersey the past few days, but that nothing had been agreed upon.
Nets coach Avery Johnson wouldn't let the talk be a distraction for his team.
"With us, we're just focused on basketball. We're focusing on the things that we can control on the court," he said. "Hopefully whatever is being talked about will get resolved at some point. But for me as the coach, I'm just focusing on getting our guys ready to play our first preseason game on the 17th. And whoever shows up in camp, whatever day they show up, obviously we're not finished with our roster.
"But in the meantime, we're getting guys ready to play."
Chris Broussard is a senior writer for ESPN The Magazine. Information from ESPNNewYork.com contributor Mike Mazzeo was used in this report.